A lung CT scan can identify lung cancer and small nodules, infections (pneumonia, TB), pulmonary emboli on CT pulmonary angiography, emphysema/COPD changes, interstitial lung disease and fibrosis, bronchiectasis, pleural effusion or thickening, enlarged lymph nodes, calcifications, and traumatic injuries. It also helps monitor disease progression, treatment response, airway inflammation, and some congenital abnormalities.

Abnormal CT findings in the lungs include solitary or multiple nodules or masses, ground‑glass opacities, focal consolidation (pneumonia), interstitial thickening or fibrosis, bronchiectasis, emphysematous changes, pleural effusion, enlarged mediastinal or hilar lymph nodes, and signs of pulmonary embolism. These findings require correlation with symptoms, history, and often further testing to determine cause and management.

CT is generally better for evaluating the lungs because it gives high-resolution images of air-filled lung parenchyma, detects small nodules, pneumonia, and pulmonary embolism (with CT angiography). MRI avoids ionizing radiation and helps assess the mediastinum, chest wall, or vascular structures, but has lower sensitivity for lung tissue and is limited by motion. Choice depends on the clinical question.

After a lung CT, preliminary images are available immediately, but the radiologist's formal report usually takes 24 to 48 hours. Urgent or suspicious findings are typically communicated to your clinician right away. Many centers provide results the same day or within a few days; routine outpatient reports may take up to five to seven days. If you haven’t received results within a week, contact the imaging center or your doctor.

A lung CT scan is generally safe for most people. It uses more radiation than a chest X‑ray, so risks are small but increase with repeated scans. Contrast dye can rarely cause allergic reactions or affect kidney function. Benefits usually outweigh risks when diagnosing or monitoring lung disease. Pregnant women should avoid it unless essential; discuss alternatives and individual risk with your doctor.

If a CT shows a life‑threatening or critical finding, the radiologist will usually notify the treating team immediately—often within minutes to an hour. Hospitals with 24/7 emergency radiology provide rapid preliminary reads; a formal written report typically follows within a few hours. Routine, non‑urgent CT reports may take 24 hours or longer.